1. Field of the Invention
The present invention relates to a recording material and more particularly to a recording material inhibited from alteration.
2. Related Art
Hitherto, many chemical color formation systems have been known which utilize recording energies such as heat, pressure, light, and electricity. Among them, the color formation system of two-component type comprising a normally colorless or light colored dye precursor and a color developer which reacts with the dye precursor to form a color has been known for a long time and has been widely utilized as a recording material.
For example, there are heat-sensitive recording materials utilizing heat energy, pressure-sensitive recording materials utilizing pressure energy and electro-thermal recording materials utilizing electrical energy.
Especially, the pressure-sensitive recording materials have been generally used like normal papers. In general, the pressure-sensitive recording materials comprise an upper sheet prepared by coating, on a substrate, microcapsules formed by emulsifying a solution of a dye precursor in a suitable solvent to a few microns and then microencapsulating the emulsion, a lower sheet prepared by coating a color developer layer containing a color developer on a substrate and others. The microcapsules coated side and the color developer coated side are brought into contact with each other and when the thus superimposed upper and lower sheets are applied with writing pressure or striking pressure, the microcapsules are ruptured to release the content containing the dye precursor, which transfers to the color developer layer to contact with the color developer and form a color, thereby to form a recorded image.
The heat-sensitive recording materials generally comprise a substrate and, provided thereon, a heat-sensitive recording layer mainly composed of a normally colorless or light colored dye precursor and a color developer. Upon heating by a thermal head, a thermal pen, a laser beam or the like, the dye precursor and the color developer instantaneously react with each other to form a recorded image. These are disclosed in Japanese Patent Kokoku Nos. 43-4160 and 45-14039. These heat-sensitive recording materials have the advantages that records can be obtained by relatively simple devices, maintenance is easy and noise is not generated and they are utilized in a wide variety of the fields such as instrumentation recorders, facsimiles, printers, terminals of computers, labels, vending machines for passenger tickets and the like.
For example, they are utilized for payment slips in banking establishments, for flight tickets and passenger tickets and besides, those which have a magnetic recording layer on the back (a side of the substrate opposite to the side a heat-sensitive recording layer is provided) are utilized for magnetic passenger tickets, magnetic commuter passes, magnetic parking tickets, pre-paid cards and the like.
These uses are concerned with monetary exchange and various measures for prevention of alteration have been devised.
Recording systems which use fluorescent materials for prevention of alteration include heat transfer recording sheets, and there have been various examples as disclosed, for example, in Japanese Patent Kokai Nos. 59-54598 and 61-228994.
Japanese Patent Kokai No. 59-54598 relates to a heat-sensitive fluorescent transfer medium comprising a substrate and, provided thereon, a heat-sensitive transfer ink layer containing a fluorescent pigment and a hot-melt adhesive. In such heat-sensitive fluorescent transfer mediums, a fluorescent pigment is used as a colorant and this is for carrying out visual identification with the hue possessed by the fluorescent pigment and for showing up the strong fluorescence. However, there is the defect that visual identification is difficult with the hue of the fluorescent pigment per se. Moreover, in order that visual identification can be performed, a large amount of the fluorescent pigment must be contained therein, resulting in increase of costs.
Japanese Patent Kokai No. 61-228994 relates to a heat transfer recording medium comprising a heat resistant support and, provided thereon, a heat meltable ink layer mainly composed of a colorant, a wax, a binder and a softening agent wherein a fluorescent material is contained in the ink layer and besides, the colorant is one which absorbs little or no fluorescence of the fluorescent material. This aims at solving the defect that the fluorescence of the fluorescent material is absorbed by the colorant to cause reduction of fluorescent intensity. This patent publication illustrates that it is preferred to use the colorant and the fluorescent material of the same color type and red color type colorants for red color type fluorescent materials are mentioned and similarly, blue type and yellow type are mentioned. That is, the recording medium is characterized in combination of colorants and fluorescent materials of the same color type and does not use a combination of different color types. Furthermore, this patent publication has no disclosure relating to a black record image.
As explained above, heat transfer recording sheets comprising a substrate, a heat resistant layer coated on one side of the substrate and a heat meltable ink layer coated on another side of the substrate, a fluorescent material being contained in the heat meltable ink have had various problems for prevention of alteration and regarding inherent properties of recording materials. Besides, these techniques relate to heat transfer recording where fluorescent pigments are contained in the heat meltable ink and these recording materials are restricted in their use.